Unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In a typical teleconference, the participants are in different locations. These locations may be referred to as the “near end” and the “far end”. (Note that the designations “near end” and “far end” are relative in order to provide a perspective for this discussion.) In general, the near end device outputs the sound from the far end; the near end device also receives sound input for transmission to the far end. The far end device operates in a similar manner.
Many near end devices include a sidetone generator. The “sidetone” refers to a portion of the near end sound that is also output at the near end. The sidetone generator outputs the sidetone in order for the near end user to receive feedback on the sounds originating at the near end. (User experience studies show that without the sidetone, near end users can perceive a sense of isolation and that the communication channel to the far end is weak or inoperative.) The sidetone is usually generated when the near end device is operating as a handset or headset; the sidetone is usually not generated when the near end device is operating as a speaker phone, due to potential feedback.
Often the different locations involved in the teleconference will have different acoustic environments. For example, one group of participants may be in a conference room, and the other participant may be in a small office room; the conference room will often be more reverberant than the small office room. Similarly, the conference room participants may be using a speaker phone, and the small office room participant may be using a telephone handset; the speaker phone will receive a more reverberant input than the telephone handset. The difference in reverberation is even greater when one of the participants is using a headset, which generates very little reverberation, if any (referred to as a “dry” acoustic environment).